The times and the technologies are changing day by day. The relative technologies of electronic devices are progressing daily. The functions of electronic products are also enhanced abruptly. Relatively, the computer peripherals are expanded more and more quickly to provide the required convenience in daily life. The scanner is a commonly computer peripheral. The main function of the scanner is to retrieve an image of a scanned document and convert the retrieved image into electronic signals. And, the electronic signals are input to a computer to proceed image treatment.
Please refer to FIG. 1, which is an embodiment for a typical optical scanner 1 commonly seen in current market. A document window glass 15 for supporting a document 30 to be scanned is arranged on the upper side surface of a shell body 11 of the optical scanner 1. A scanning module 14 driven by a driving device 12 proceeds a linear motion along the direction of a guiding rod 13 inside the shell body 11 to execute an image scanning job to the document 30 placed on the document window glass 15.
Please refer to FIG. 2A to FIG. 2C, which are the execution embodiments for the automatic document feeder carried by an optical scanner commonly seen in current market. Wherein the automatic document feeder 2 is arranged on the upper side of the prior optical scanner 1 to provide scanning job for the automatically fed document 30. When processing the automatically document-feeding scanning, the scanning module 14 moves along the guiding rod 13 to a lower edge of the optical scanner 1 and is secured thereof. The document 30 is driven into the position of the scanning window 16 by the friction force of the rotation motion of the roller set 21. The motion of automatic document feeding and scanning is then completed.
When the document 30 is placed by the prior automatic document feeder 2, because the document 30 placed in slant way or the change of friction coefficient on the surface of the roller set 21 due to frequent usage, a slant is generated on the document driven by the non-uniform friction force applied by the roller 21. A slant document 30 will be scanned and an erroneous or mistaken scanned product is completed. Therefore, it must depend on personnel observe for changing or give up the scanning job of the automatic document feeder. So, it wastes lots of human power, time and material means. Above-mentioned problems are really needed to be solved among persons or industries to reduce the cost paid by the person or society and promote the industrial competition abilities of the country. Therefore, the break-through and solution for this problem is really urgent.
To break-through and solve the above problem, several relative makers proposed that a plurality of black-line-patterns be arranged on the automatic document feeder. Please refer to FIG. 3A to FIG. 3F, which show that the automatic document feeder 2 has plural black-line-patterns 23 of left-and-right symmetry corresponding to the scanning window 16 of the optical scanner 1. The automatic document feeder 2 feeds the document 30 in. After reading the image variation of the black line patterns 23, the time is counted by a timer (not shown in the drawing) that is set with a preset value, through an appropriate time, the document 30 is detected. When the document 30 is fed in a slant way, only one side of the black line patterns is blocked by the document 30, so the motion will be stopped and an alarm is set off. When the document 30 is fed in normal way, two sides of the patterns will all be blocked by the document 30, a second detection will be executed for ensuring that no error happened and then a scanning is executed.
But to solve the above problem, not only are complicated detection steps required, but also an increase of accessories for scanners is needed It is also impossible to accurately detect the slant quantity of the document. Since a single arrangement is only for a single machine, so for various scanners, a wide availability can not be obtained. Therefore, the prior solution can not appropriately and completely fulfill the requirement for the manufacturing industries. The problem still can not get a suitable solution that is urgently required by the manufacturing industries to promote the technology.